JPS635682B2 - - Google Patents
Info
- Publication number
- JPS635682B2 JPS635682B2 JP57052649A JP5264982A JPS635682B2 JP S635682 B2 JPS635682 B2 JP S635682B2 JP 57052649 A JP57052649 A JP 57052649A JP 5264982 A JP5264982 A JP 5264982A JP S635682 B2 JPS635682 B2 JP S635682B2
- Authority
- JP
- Japan
- Prior art keywords
- wavelength
- interference fringe
- refractive index
- light
- atmosphere
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 18
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 238000005305 interferometry Methods 0.000 claims 1
- 238000005259 measurement Methods 0.000 description 8
- 238000000691 measurement method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
- G01B9/02007—Two or more frequencies or sources used for interferometric measurement
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Description
本発明は、大気中での高精度干渉測長法に関
し、より詳しくは、測長寸法を媒質としての空気
の屈折率の影響を受けない値として高精度に測定
する方法に関するものである。
従来、マイケルソン干渉計による干渉測長の原
理に基づいて、
2nL＝mλ
ｎ：媒質（空気）の位相屈折率
Ｌ：測長寸法
ｍ：干渉縞次数
λ：光の波長
として表わされる式における干渉縞次数ｍを測定
し、それによつて寸法Ｌが測定されている。しか
るに、上記寸法Ｌを定めるために用いる屈折率ｎ
は、別個に設けた真空干渉計等により測定され、
あるいは空気の圧力、気温等の測定結果に基づい
て分散式から求められているため、屈折率を求め
る光路と現実に測定を行う場所が異なり、たとえ
測定場所としての部屋の空気を一定の状態として
も、上記測定場所における屈折率を精度良く求め
ることができない。
本発明は、このような問題を解決するためにな
されたもので、干渉計による測長を、光の媒質と
しての空気の屈折率を含まない演算によつて求め
ることにより、その測定値の精度を向上できるよ
うにした方法を提供しようとするものである。
上記目的を達成するため、本発明の大気中での
高精度測長法は、波長λ1とそれよりも少し小さい
波長λ2の光束をそれらの光軸をそろえて干渉計に
入射し、上記一対の波長の合成波長の光束による
干渉縞次数と、上記一方の波長の光束による干渉
縞次数とをそれぞれ検出し、それらの干渉縞次数
に基づいて、移動鏡の変位量として与えられる測
長寸法を媒質としての大気の屈折率の影響を受け
ない値として求めることを特徴とするものであ
る。
以下に本発明の方法の原理を説明する。
波長λ1の光束の干渉は、
2n1L＝m1λ1 …(1)
n1：空気の位相屈折率
m1：干渉縞次数
として表わされ、また波長λ1とそれよりも少し小
さい波長λ2の光束を、それらの光軸をそろえて干
渉計に入射した場合における干渉は、本発明者が
先に提案した「群屈折率の高精度測定方法」（特
λs＝λ1λ2／λ1−λ2
The present invention relates to a high-precision interferometric length measurement method in the atmosphere, and more particularly to a method for measuring a length dimension with high precision as a value that is not affected by the refractive index of air as a medium. Conventionally, based on the principle of interferometric length measurement using a Michelson interferometer, 2nL=mλ n: phase refractive index of medium (air) L: length measurement m: interference fringe order λ: interference in the formula expressed as wavelength of light The fringe order m is measured and thereby the dimension L is determined. However, the refractive index n used to determine the above dimension L
is measured by a separately installed vacuum interferometer, etc.
Or, because it is calculated from a dispersion formula based on the measurement results of air pressure, temperature, etc., the optical path used to determine the refractive index differs from the actual measurement location, even if the air in the room where the measurement is made is in a constant state. However, it is not possible to accurately determine the refractive index at the measurement location. The present invention was made to solve such problems, and the accuracy of the measured value is improved by calculating the length measured by the interferometer using calculations that do not include the refractive index of air as a light medium. The aim is to provide a method that can improve the In order to achieve the above object, the high-precision length measurement method in the atmosphere of the present invention involves beams of wavelength λ 1 and slightly smaller wavelength λ 2 being incident on an interferometer with their optical axes aligned. The interference fringe order due to the light beam of the combined wavelength of the pair of wavelengths and the interference fringe order due to the light beam of one of the wavelengths are detected respectively, and the measurement dimension is given as the amount of displacement of the movable mirror based on these interference fringe orders. is characterized in that it is determined as a value that is not affected by the refractive index of the atmosphere as a medium. The principle of the method of the present invention will be explained below. The interference of light beams with wavelength λ 1 is expressed as 2n 1 L=m 1 λ 1 …(1) n 1 : phase refractive index of air m 1 : interference fringe order, and wavelength λ 1 and slightly smaller than that. The interference when light beams of wavelength λ 2 are incident on an interferometer with their optical axes aligned can be determined by the ``high-precision measurement method of group refractive index'' (special λ s = λ 1 λ 2 /λ 1 −λ 2
【表】
によつて与えられるので、
ng−１／ng−n1＝（n1−１）0／（ng−n1）0≡Ａ（Ａ：
不変量）…（3b）
が成り立つ、ここで、ａは空気の密度係数であ
り、（n1−１）0および（ng−１）0は、標準状態に
おける屈折率である。これらの(1)〜(3)式から寸法
Ｌは、
Ｌ＝msλs／２−Ａ（msλs−m1λ1）／２ …(4)
として、空気の屈折率を含まない形で表わされる
ため、寸法Ｌを空気の屈折率の影響を受けない
値、即ち空気の屈折率の変化を自動的に補正した
高精度な値として得ることができる。
上記原理に基づいて寸法Ｌ（移動鏡の変位量）
を求めるには、波長λ1とそれよりも少し小さい波
長λ2の光束を光軸をそろえて干渉計に入射し、そ
れらの光束をビームスプリツターにより異なる光
路を通る二つの光束に分離した後再び光軸をそろ
えて合成し、上記光路の一方における移動鏡を変
化させてその光路長を増減した場合における上記
合成光束中の合成波長の光束及び波長λ1の光束の
それぞれの干渉縞次数の変化を検出し、それらの
干渉縞次数の測定値に基づいて、上記移動鏡の変
位量を媒質としての大気の屈折率を含まない演算
により求めるようにすればよい。
第１図は上記原理に基づいて測長を行う干渉計
を示すものである。同図の干渉計においては、波
長λ1のレーザ光源１及び波長λ2のレーザ光源２を
備え、これらの光源からのレーザ光はハーフミラ
ー等からなるビーム混合器３において混合され
る。上記レーザ光源１，２としては、例えば
0.633μｍHe−Neレーザと0.612μｍHe−Neレー
ザを用い、あるいは0.5145μｍArイオンレーザと
0.488μｍArイオンレーザを用いることができ、
さらに色素レーザなどの２波長同時発振レーザを
用いることもできる。
これらの光源からのレーザ光は、光軸をそろえ
て干渉計に入射され、即ちコリメータ４を経てハ
ーフミラー等からなるビームスプリツター５に投
射され、ここで可変形光路増倍器６に向う反射光
と、固定形光路増倍器７に向う透過光に分割され
る。これらの光路増倍器６，７は、移動鏡６ａと
固定鏡６ｂあるいは固定鏡７ａ，７ｂ同士の対向
により構成され、入射した光をそれらの鏡の間で
の多数回の反射と反射鏡６ｃ，７ｃにおける反射
の後、入射光路から射出し、それにより光路をＭ
倍（図示の装置においてはＭ＝５）に増倍するよ
うに機能するものである。上記可変形光路増倍器
６においては、移動鏡６ａを変位させることによ
り、その変位Ｌを2M倍にすることができ、従つ
てこの増倍器６を用いた場合には、上記(4)式は、
Ｌ＝msλs／2M−Ａ（msλs−m1λ1）／2M …(5)
として表わされることになる。上記光路増倍器
６，７からの射出光は、それぞれもとの光路を戻
つてビームスプリツター５に入り、このビームス
プリツター５を透過または反射して光軸が一致し
た後、さらに他のビームスプリツター８により反
射光と透過光に分けられる。反射光は、波長λsの
光束の干渉縞次数msを求める回路に入射され、
また透過光は波長λ1の光束の干渉縞次数m1を求
める回路に入射される。即ち、上記反射光は検出
器１１に入射して、波長λsの光束による干渉縞が
検出され、それを増幅器１２、自乗器１３、及び
フイルター１４に通すことによりコントラストを
強めた後、位相ロツク１５に入力して400倍され
た状態で干渉縞の位相を固定し、その後外部から
基準となる目盛線信号Ｓを入力させたゲート１６
を通して干渉縞次数msに応じた信号が出力され、
それが次段のカウンター１７でカウントされる。
これと並行して、上記透過光は、波長λ1のみの光
束を透過させるフイルター２１を通して検出器２
２に入力され、波長λ1の光束による干渉縞が検出
され、それが増幅器２３で増幅された後、位相ロ
ツク２４に入力して、100倍された状態で干渉縞
の位相が固定され、前記目盛線信号Ｓで制御され
るゲート２５を通して干渉縞次数m1に応じた信
号が出力され、それが次段のカウンター１７によ
りカウントされる。而して、このようにして得ら
れた干渉縞次数ms、m1により上記(5)式から測定
距離Ｌが求められる。
なお、補正精度に関する計算例を示すと、前記
He−Neレーザを用いた場合、λ1＝0.633μｍ、λ2
＝0.612μｍ、λs＝18.45μｍ、Ａ＝33.88となり、こ
れらを(5)式から得られる
δL＝Ａ（δmsλs＋δm1λ1）／2M
に代入し、δms＝1/200、sm1＝1/100、Ｍ＝５とす
ると、δL＝0.32μｍとなる。
以上に詳述したところから明らかなように、本
発明によれば、極めて簡単な手段によつて容易に
測長を行うことができ、しかもその測長寸法は媒
質としての大気の屈折率を含まない演算により求
められるので、媒質における屈折率の変化に拘ら
ず、それを自動的に補正して高精度なものとして
得ることができる。[Table] Since n g −1/n g −n 1 = (n 1 −1) 0 / (n g −n 1 ) 0 ≡A(A:
(invariant)...(3b) holds, where a is the density coefficient of air, and (n 1 -1) 0 and (n g -1) 0 are the refractive indices in the standard state. From these formulas (1) to (3), the dimension L is calculated as L=m s λ s /2−A(m s λ s −m 1 λ 1 )/2 (4), including the refractive index of air. Therefore, the dimension L can be obtained as a value that is not affected by the refractive index of air, that is, a highly accurate value that is automatically corrected for changes in the refractive index of air. Based on the above principle, dimension L (displacement amount of moving mirror)
To calculate The interference fringe order of each of the light beam of the combined wavelength and the light beam of wavelength λ 1 in the above-mentioned combined light beam when the optical axes are aligned and combined again, and the optical path length is increased or decreased by changing the movable mirror on one of the optical paths. The change may be detected, and the amount of displacement of the movable mirror may be calculated based on the measured values of the interference fringe orders by calculation that does not include the refractive index of the atmosphere as a medium. FIG. 1 shows an interferometer that measures length based on the above principle. The interferometer shown in the figure includes a laser light source 1 with a wavelength λ 1 and a laser light source 2 with a wavelength λ 2 , and the laser lights from these light sources are mixed in a beam mixer 3 consisting of a half mirror or the like. As the laser light sources 1 and 2, for example,
Using a 0.633μm He-Ne laser and a 0.612μm He-Ne laser, or a 0.5145μm Ar ion laser.
A 0.488μm Ar ion laser can be used,
Furthermore, a two-wavelength simultaneous oscillation laser such as a dye laser can also be used. The laser beams from these light sources are incident on the interferometer with their optical axes aligned, that is, they are projected onto a beam splitter 5 consisting of a half mirror or the like through a collimator 4, where they are reflected toward a variable optical path multiplier 6. The transmitted light is split into light and transmitted light towards a fixed optical path multiplier 7. These optical path multipliers 6 and 7 are composed of a movable mirror 6a and a fixed mirror 6b or fixed mirrors 7a and 7b facing each other, and the incident light is reflected many times between these mirrors and reflected by a reflecting mirror 6c. , 7c exits the incident optical path, thereby changing the optical path to M
It functions to multiply by a factor of two (M=5 in the illustrated device). In the above variable optical path multiplier 6, by displacing the movable mirror 6a, the displacement L can be multiplied by 2M. Therefore, when this multiplier 6 is used, the above (4) The equation will be expressed as L=m s λ s /2M−A(m s λ s −m 1 λ 1 )/2M (5). The emitted lights from the optical path multipliers 6 and 7 respectively return to their original optical paths and enter the beam splitter 5, and after being transmitted or reflected through this beam splitter 5 so that their optical axes coincide, they are further transmitted to another optical path. The beam splitter 8 separates the light into reflected light and transmitted light. The reflected light enters a circuit that calculates the interference fringe order m s of a light beam with wavelength λ s ,
The transmitted light is also input to a circuit for determining the interference fringe order m 1 of the light beam with wavelength λ 1 . That is, the reflected light enters the detector 11, and interference fringes due to the light beam of wavelength λ s are detected, and after passing through an amplifier 12, a squarer 13, and a filter 14 to enhance the contrast, a phase lock is applied. 15, the phase of the interference fringe is fixed in the state multiplied by 400, and then a scale line signal S serving as a reference is inputted from the outside to the gate 16.
A signal corresponding to the interference fringe order m s is output through
This is counted by the counter 17 on the next stage.
In parallel with this, the transmitted light passes through a filter 21 that transmits a light beam with only a wavelength λ 1 , and then passes through a detector 2.
2, the interference fringes due to the light beam of wavelength λ 1 are detected, and after being amplified by the amplifier 23, the interference fringes are inputted to the phase lock 24, where the phase of the interference fringes is fixed by multiplying by 100. A signal corresponding to the interference fringe order m 1 is outputted through the gate 25 controlled by the scale signal S, and is counted by the counter 17 at the next stage. Using the interference fringe orders m s and m 1 thus obtained, the measurement distance L can be determined from the above equation (5). In addition, an example of calculation regarding correction accuracy is shown above.
When using a He-Ne laser, λ 1 =0.633μm, λ 2
= 0.612 μm, λ s = 18.45 μm, A = 33.88, and by substituting these into δL = A (δm s λ s + δm 1 λ 1 )/2M obtained from equation (5), δm s = 1/200, If s m 1 =1/100 and M=5, δL = 0.32 μm. As is clear from the detailed description above, according to the present invention, length can be easily measured by extremely simple means, and the measured length includes the refractive index of the atmosphere as a medium. Since the refractive index is determined by an independent calculation, it is possible to automatically correct the change in the refractive index in the medium and obtain a highly accurate one.
第１図は本発明の実施に用いる装置の構成図で
ある。
６ａ……移動鏡。
FIG. 1 is a block diagram of an apparatus used to implement the present invention. 6a...Moving mirror.
Claims (1)
をそれらの光軸をそろえて干渉計に入射し、上記
一対の波長の合成波長の光束による干渉縞次数
と、上記一方の波長の光束による干渉縞次数とを
それぞれ検出し、それらの干渉縞次数に基づい
て、移動鏡の変位量として与えられる測長寸法を
媒質としての大気の屈折率の影響を受けない値と
して求めることを特徴とする大気中での高精度干
渉測長法。1 Light beams of wavelength λ 1 and a slightly smaller wavelength λ 2 are input into an interferometer with their optical axes aligned, and the interference fringe order due to the beam of the combined wavelength of the above pair of wavelengths and the beam of one of the wavelengths above are calculated. It is characterized by detecting the interference fringe orders and the interference fringe orders, and determining the measured dimension given as the amount of displacement of the moving mirror as a value that is not affected by the refractive index of the atmosphere as a medium, based on those interference fringe orders. High-precision interferometry in the atmosphere.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57052649A JPS58169004A (en) | 1982-03-31 | 1982-03-31 | Highly accurate interference length measuring method in atmosphere |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57052649A JPS58169004A (en) | 1982-03-31 | 1982-03-31 | Highly accurate interference length measuring method in atmosphere |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58169004A JPS58169004A (en) | 1983-10-05 |
| JPS635682B2 true JPS635682B2 (en) | 1988-02-04 |
Family
ID=12920692
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57052649A Granted JPS58169004A (en) | 1982-03-31 | 1982-03-31 | Highly accurate interference length measuring method in atmosphere |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58169004A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004286575A (en) * | 2003-03-20 | 2004-10-14 | National Institute Of Advanced Industrial & Technology | Method and system for precisely measuring group refractive index of optical material |
| JP2007114206A (en) * | 2006-11-30 | 2007-05-10 | National Institute Of Advanced Industrial & Technology | Method for precision measurement of group refractive index of optical material |
| CN102032950A (en) * | 2010-10-15 | 2011-04-27 | 中国科学院安徽光学精密机械研究所 | Method for measuring coherent length of entire atmosphere by observing stars in daytime |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0743243B2 (en) * | 1985-04-25 | 1995-05-15 | 工業技術院長 | Phase difference detection method in interferometer |
| JPH0711406B2 (en) * | 1985-08-03 | 1995-02-08 | 株式会社ニコン | High precision interferometer device |
| JPH0198902A (en) * | 1987-10-12 | 1989-04-17 | Res Dev Corp Of Japan | Light wave interference length measuring instrument |
| JPH01210803A (en) * | 1988-02-19 | 1989-08-24 | Kitamura Mach Co Ltd | Laser length measuring method |
| JPH0820235B2 (en) * | 1991-04-26 | 1996-03-04 | 新技術事業団 | Straightness measuring device |
| US5825493A (en) * | 1996-06-28 | 1998-10-20 | Raytheon Company | Compact high resolution interferometer with short stroke reactionless drive |
| CN1304879C (en) * | 2005-06-23 | 2007-03-14 | 哈尔滨工业大学 | Bidimension photoelectric self collimating device based on optical length multiplication compensation method and its measuring method |
-
1982
- 1982-03-31 JP JP57052649A patent/JPS58169004A/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004286575A (en) * | 2003-03-20 | 2004-10-14 | National Institute Of Advanced Industrial & Technology | Method and system for precisely measuring group refractive index of optical material |
| JP2007114206A (en) * | 2006-11-30 | 2007-05-10 | National Institute Of Advanced Industrial & Technology | Method for precision measurement of group refractive index of optical material |
| CN102032950A (en) * | 2010-10-15 | 2011-04-27 | 中国科学院安徽光学精密机械研究所 | Method for measuring coherent length of entire atmosphere by observing stars in daytime |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58169004A (en) | 1983-10-05 |
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